This commit introduces support for read only slaves via redis.conf and CONFIG GET/SET commands. Also various semantical fixes are implemented here:

1) MULTI/EXEC with only read commands now work where the server is into a state where writes (or commands increasing memory usage) are not allowed. Before this patch everything inside a transaction would fail in this conditions.

2) Scripts just calling read-only commands will work against read only
slaves, when the server is out of memory, or when persistence is into an
error condition. Before the patch EVAL always failed in this condition.

Now Lua scripts dispatch Redis commands properly calling the call() function. In order to make this possible call() was improved with a new flags argument that controls how the Redis command is executed.

clean REDIS_DIRTY_CAS when discard Command runs. otherwise the next MULTI/EXEC may fail in the same RedisClient 

Take a pointer to the relevant entry of the command table in the client structure. This is generally a more sounding design, simplifies a few functions prototype, and as a side effect fixes a bug related to the conversion of EXPIRE -1 to DEL: before of this fix Redis tried to convert it into an EXPIREAT in the AOF code, regardless of our rewrite of the command.

networking related stuff moved into networking.c

moved more code

more work on layout of source code

SDS instantaneuos memory saving. By Pieter and Salvatore at VMware ;)

cleanly compiling again after the first split, now splitting it in more C files

moving more things around... work in progress

split replication code

splitting more

Sets split

Hash split

replication split

even more splitting

more splitting

minor change